Transferable magnetic coating composition and transfer web coated therewith



April 30, 1963 WAX COATING COATING LAYER CONTAINING I POLYSILOXANE RESIN, POLYSILOXANE AGUM, AND IRON OXIDE PARTICLES FILM OR WEB BASE INVENTOR MARK V. FOG E m g/W HIS ATTORNEYS United States Patent This invention relates to a transferable magnetic coating composition and to a transfer web coated therewith.

'Dhe transfer web coated with the novel coating composition is used, coated side against a receiving material surface, and the transfer of (the coating material is [brought about by the impact of a type, or other marking instrument, in selected areas, applied either to the back of the transfer web or to the back of the receiving material, to cause break-away of the coating from the web and adherence of such brokenaaway material to the receiving surface.

it is important that as much magnetic material be transfer-red cleanly and well defined by the marking instru ment as is possible, consistent with the area of [the mark to be made, so that the largest possible signal may be magnetically impressed on and sensed from a given recorded mark, and it is a main feature of this invention that complete transfer of the magnetic material be made to the receiving surface. It is within the bounds of use of this coated trans-fer web to pre-m-agnetize it so the transferred material is already in a magnetized condition or the magnetic material may be magnetized in the desired polarity after being transferred. It will be apparent that the marking instrument itself, if made of magnetizable material, could be used to magnetize the transferred material in the desired polarity as it is being transferred. The FIGURE in the drawing exemplifying the product of this invention is a cross-sectional view of a film or web base material coated with a first layer containing a homogeneous blend of a solid polysiloxane resin, a linear polysiloxane gum, and magnetic iron oxide particles, said first layer being overcoated with a thin second layer of wax.

In the best practice, the web material on which the novel transfer composition is coated is thin paper, thin foil of metal, or thin film of film-forming polymer material, that, because of its thinness and pliability, responds to the marking impacts applied thereto, the consequent distortion of the base web material aiding in the breakaway of the magnetic coating composition therefrom, and its transfer and adherence to the receiving surface.

The magnetic component of the magnetic coating composition is dispersed in a binder material dissolved in a readily evaporable liquid vehicle to form a solution-dispersion that may be applied to a supporting web material and dried to a solid coating at room temperature. The binder material is a pliable linear dimethyl-siloxane polymer which has had mixed therewith an embrittling compound of the polysiloxane methyl and/or methyl-phenyl derivative type, the polysiloxane structure giving the embrittling characteristics to it.

After the base web has been coated with the magnetic coating composition, and allowed to dry, an over-coating of a waxy material such as paraffin wax of a fraction that is solid at room temperature (about degrees centigrade), is applied in a very thin coating to prevent the blocking or sticking together of the turns of a coil of such coated web and, additionally, to aid in the adherence of the transferred magnetic composition to the receiving surface.

3,087,832 Patented Apr. 30,, 1963 The linear dimethyl-siloxane polymer has the general formula and is of such length as to give the material pliability in the hands, at room temperature (ZOdegrees centigrade). This polymer is a clear viscous gum with a plasticity number ranging from to 120 as measured with the Williams plasticity number test (AST-M, D926, room temperature for three minutes.

The solid embrittling resin that preferably is used is the mentioned methyl and/ or methyl-phenyl polysiloxane having the general formula Grams Toluene 5200 Dimethyl-siloxane polymer gum SE-76 605 Polysiloxane resin R-S 071, as disclosed in United States Patent No. 2,718,483 336 Black magnetic iron oxide powder 1043 and plasticized with a compatible silicone oil, if necessary, to achieve the required transfer and handling characteristics. It will be apparent that the iron oxide constitutes about half of the solids of the preferred composition, by weight, and that of the other solids which constitute the binder, the resin consitutes about one-third, although great variations are permissible in these relative amounts. The characteristic sought for in the coating on the web is its easy and complete transfer from the supporting web to the receiving surface.

The foregoing composition is applied to the supporting web, as a liquid slurry, to give a coating, when dried, of about 0.0001 of an inch. On top of the dried coating is coated a film of paraflin wax, which coating need not be more than 0.00005 of an inch in thickness. Tissue paper, such as is used in making carbon transfer sheets, of a thickness of 0.0005 of an inch, makes a very suitable supporting web. Yoshino paper is commonly used for such a web.

The foregoing preferred example may be modified considerably with regard to the relative proportions of material used. For instance, the variations of the relative amounts of materials used may well be within the following percentages, by weight:

Dimethyl-silicone polymer, as specified, up to 60 Polysiloxane resin, as specified, up to 50 Black magnetic iron oxide, or equivalent, up to Toluene, or other rapidly evaporable vehicle, to make a coating slurry.

characteristics, or characteristics more to be desired for a particular intended use. Among the magnetic material 3. substitutes for iron oxide are ferrite materials, cobaltnickel alloys, iron, steel, and the like, in powdered form.

It is well known to use powdered magnetic materials in a transfer composition andin transfer webs coated with such as disclosed in United States Patent No. 2,744,031, which issued on the application of Robert E. Mumma, May 1, 1956, the novelty of the present invention over what is disclosed in said patent, being the use of such magnetic materials in combination with the named silicone derivative polymers which give greatly improved transfer characteristics.

What is claimed is:

1. As an article of manufacture, a thin pliable web of transfer coating supporting material having coated on a surface thereof a mixture of black magnetic iron oxide powder and a binder material consisting of linear dimethyl silicone polymer gum and a solid polysiloxane resin as. an embrittling component, the iron oxide constituting about half the weight of the coating and the resin about one-third the weight of the binder, the outer surface of the coating having a thin coating of wax to aid in the adherence of the iron oxide and binder to a receiving sheet.

2. A coated web as in claim 1 in which the coating is modified by the addition thereto of a plasticizing silicone oil to give it the desired consistency.

3. A transfer coating for liquid application to a transfer Web at room temperature and which will dry to a solid film thereon at room temperature, consisting of, in proportional parts by weight: 605 parts of a linear dimethyl siloxane polymer gum; 336 parts of solid methylphenyl substituted polysiloxane resin; 1,043 parts of black magnetic iron oxide powder; and a sulficient amount of rapidly-evaporable vehicle to make a coating slurry.

References Cited in the file of this patent UNITED STATES PATENTS 2,744,031 Mumma May 1, 1956 2,777,781 Kordig Jan. 15, 1957 2,820,717 Newman Jan. 21, 1958 2,866,711 Hart Dec, 30, 1958 2,875,098 Blatz Feb. 24, 1959 2,912,344 Newman et a1 Nov. 10, 1959 

1. AS AN ARTICLE OF MANUFACTURE, A THIN PLIABLE WEB OF TRANSFER COATING SUPPORTING MATERIAL HAVING COATED ON A SURFACE THEREOF A MIXTURE OF BLACK MAGNETIC IRON OXIDE POWER AND A BINDER MATERIAL CONSISTING OF LINEAR DIMETHYL SILICONE POLYMER FUM AND A SOLID POLYSILOXANE RESIN AS AN EMBRITTLING COMPONENT, THE IRON OXIDE CONSITUTING ABOUT HALF THE WEIGHT OF THE COATING AND THE RESIN ABOUT ONE-THIRD THE WEIGHT OF THE BINDER, THE OUTER SURFACE OF THE COATING HAVING A THIN COATING OF WAX TO AID IN THE ADHERENCE OF THE IRON OXIDE AND BINDER TO A RECEIVING SHEET. 